Relay



May 3 a 1 R.BROOK$ RELAY Filed April 9. 1920 J E m wumsssss; F INVENTOR @gerf firookr.

Registered May 3, 1927.

UNITED STATES PATENT OFFICE.

ROBERT BROOKS, OF ASHTON-ON-MERSEY, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

RELAY.

Application filed April 9, 1920, Serial No. 372,40 and in Great Britain April 11, 1819.

My invention relates to relays and particularly to time-liinit-overload relays.

One object of my invention is to provide a relay in which the operation of the relay under an overload is governed by a combination of an inverse-time-element feature with a definite time-limit feature by which means on moderate overloads the time of operation, varies substantially inversely as the strength of the overload current, whereas on severe overloads or short-circuits the action of the relay is prevented from being instantaneous by reason of the definite time 'feature. Relays of this description with varying time limits may be so arranged in series that they will operate in a predetermined sequence whether the overload be moderate or so severe as to amount to substantially a short-circuit.

In practicing my invention, I provide a coil or solenoid that actuates a core or plunger to which is attached a bucket or receptacle immersed in mercury that is contamed in a reservoir. The bucket is provided with an opening near the bottom throu h which the mercury may fiow out of t e bucket into the reservoir when the former is lifted by the plunger. The relay circuit is arranged to pass through the mercury in the reservoir and will always be broken when the bucket has been lifted'from the reservoir and the stream of mercury connecting the bucket and the reservoir ceases.

In the accompanying drawings, Figure 1 is a. side View, partially. in elevation and partially, in section, of, the device e1nbody ing my invention; Fig. 2 is a side elevational view of the relay shown in Fig. 1; Fig. 3 is a diagrammatic View of an electric circuit embodying the relay shown in Fig. 1, and Fiv. 4 is adiagrammatic view of a circuit embo ying a modified form' of the relay shown in Fig. 1.

Referring to 3, which illustrates the parts of a relay, the completion of the operation of which is adapted to break a normally closed circuit, an overload coil or solenoid 1 is arranged to act upon a core or plunger 2 to which .is attached, by means of a rod 3, a bucket 4 immersed in mercury 5 in a reservoir 6. The tripping circuit which is normally completed through the relay is indicated at 7 and is shown diagrammatically as assing through the plunger 2, rod 3 and ucket 4 into the mercury and thence through the reservoir 6. The bucket has a comparatively small orifice 8 at the bottom through which the mercury in the bucket may escape when the bucket is raised clear of the mercury in the reservoir.

The operation of the device is as follows. Upon the occurrence of an overload in the main circuit, which the relay is arranged to protect, the o eration coil 1 becomes enc gined sufiicient y to attract the plunger 2 and raise the bucket 4, which contains a quantity otmercury. If only a moderate overload obtains, the rise of the bucket causes a difference of level between the mercury in the bucket and the mercury remaining in the reservoir 6, with the result'that the effective weight of the plunger 2 so increases as to retard the upward motion of the bucket. At the same time, the difference of level referred to, produces a'static pressure that causes a flow-of mercury from the bucket into the reservoir and that tends to readjust the levels of the liquid in the bucket and reservoir, respectively. This action so reduces theweight acting on the plunger that the upward movement is permitted to continue slowly until finally the bucket is drawn completely out of the mercury. At this stage there may still be some mercury in the bucket, which will continue to flow and maintain the relay circuit until the stream of mercury ceases. If the overload is severe, due, for example, to a short-circuit, the plunger will be raised very quickly and the ucket substantiall drawn immediately out of the mercury, be ore any mercury has time to flow out. The interval oftime then elapsing before the relay circuit is interrupted will therefore be determined by the quantity of mercury in the bucket and the size of the orifice through which it escapes.

' Referring now to Figs. 1 and 2, in which similar parts are denoted by the same reference numerals as in Fig, 3;, a solenoid 1 is supported by the fixed framework of the device and is provided'with a downward extension 9 in which the plunger 2 is adapted to slide. Also sliding on the downward extension 9 is a tube 10 closed at its lower end and provided with an orifice 11 through which the rod 3 may slide. The rod is provided with a flange 12 by which the plunger 2 is supported in its lowest position. The tube 10 has a projection 13 that is provided with a set screw 14 which is adapted to slide 1' iUS in a slot of a plate 16 that is so secured to the solenoid 1 that the position of the plunger 2 relatively to the solenoid 1 may be adjusted by moving the tube 10 and securing it at. the desired height by means of the screw 14. The reservoir (3 is closed by a cover 1? that has an upward tubular extension 18 attached thereto which slides on the tube 10 and may be fixed in position relatively to the in tube 10 by means of the set screw 19 which passes through a slot 20 in a plate 21 that is mounted on the tube 10. The reservoir (3 is insulated from the tube 10 by the cover 17 which is constru ted of vulcanized fibre or other such insulating material.

Itmav thus be seen that the position of the resei-voir (i relatively to the bucket- 4 may be adjustrd by means of the set screw 19 without altering the position of the plung- 2 er 2 relatively to the solenoid 1, the relative posit-ion of which is dependent on the adjustment of the tube 10 by means of the set screw 14. This construction enables the two adjustments, which are necessary in connection with the improved relay as with other relays of the same type, to be independently effected, namely the value of current at which the relay shall start into operation and the interval of time which shall elapse between the beginning of the operation and the completion thereof. In the relay described above, the first of these adjustments may b made by adjusting the position of the plunger 2 relatively to the solenoid 1 5 by means of the screw 14, as hereinbefore described, and then the second adjustment may be made by altering the position of the reservoir 6. by means of the screw 19, alteration notaffecting the adjustment pre viously made on the position of the plunger 2 in the tube 10.

The second adjustment, namely, that of the time element, may also. be. made by varying the size of the orifice 8 in the bucket 4 instead of by adjusting the. position of the bucket at in the reservoir 6.

It will be understood that, if the bucket were provided with only a small orifice, it would require a considerable interval of time to sink into the reservoir after each operation, and, in order to overcome this disadvantage, a simple form of non-return valve may be provided in the bucket in order that a rapid flow of mercury, from the reservoir 5 into the bucket, will be ensured, when the plunger falls because of p the removal or the reduction of. the magnetic attraction of the coil or solenoid for the plunger.

The relay described above is of the circuit opening type, that is, the relay circuit is opened atv the completion of the operation of the relay. The arrangemen s may, however, be easily modified, by employing additional contacts, for ezmm ple, in order that the relay circuit may be normally open and may be closed near the time of completion of the operation of the relay.

For example, as shown in Fig. l, one conductor of the tripping circuit 7 is connected to a contact member 22 that so extends below the normal level of the mercury 5 in the reservoir 6 as to cll'ect engagement therewith, and the other conductor is connected to a contact member 23 that is so disengaged from the plunger 2, when the plunger is in its normal position, that the trip circuit is normally open at this point.

Upon the occurrence of. a moderate overload, the plunger slowly raises the bucket 4 and the level of the mercury 5 outside the bucket will not be lowered sufiiciently to interrupt connection with the contact member 22. The contact member 23 is so ad justed that the plunger 2 will engage it just as the bucket is leavinv the mercury, thus completing the trip circuit which is then maintained closed until the whole of the mercury has escaped from the bucket, whereupon the trip circuit is again interrupted. Upon the occurrence, of a severe overload or short-circuit, however, the bucket 4 is immediately drawn outof the mercury. The level ofthemercury in the reservoir thereu on falls and disen 'ages the contact mem er 22. Engagement 15 cffected, however, between the contact member 23 and the plunger 2. The trip circuit '7 remains open until sufiicient mercury has escaped from the bucket to raise the level of the mercury in th'ereservoir to effect engagement between the mercury and the contactmember 22 again, whereupon the trip circuit is closed and remains closed until the mercury ceases to flow from the bucket.

It is preferred in' practice to provide an 10 auxiliary switch in the circuit of the trip coil by means of which the circuit may be interrupted when desired, after having been made by the relay. 7

It will-be understood that various modi- 110 ficat-ions may be made in the structure shown without departing from thesco e and spirit of the invention as disclosed in the a pended claims.

I c aim as my invention:

1. The method of obtaining a definite interval of time in the operation of a relay which consists in precluding engagement between a plurality of contact members un til a predetermined flow of fluid has been 120 effected through a predetermined orifice, and then maintaining the engagement effected between the contact members for an interval of time corresponding to another predetermined flow of fluid through said 125 orific 2. A time-element relay comprising "a solenoid, a core member actuated there-by,

a fluid-containing receptacl'eactuated thereby, a reservoir containing the fiuid-contain= ing receptacle and adapted to receive the fluid upon its issue from the receptacle, and means for adjusting the relations between the core member and the solenoid and between the receptacle and the reservoir to vary the operation of the relay.

3. A relay comprising an electromagnet, a fluid-containing receptacle associated therewith and provided with an aperture, a conducting fluid in said receptacle, and means including said receptacle and fluid for controlling a circuit through the fluid upon the energization of said electromagnet depending upon the flow of said liquid through said aperture, said means being so arranged that the circuit-controlling function is completed in a period of time inversely proportional to the current through said electromagnet below a certain value and definite for currents in excess of said value.

In testimony whereof, I have hereunto subscribed my name this 19th day of March 1920.

ROBERT BROOKS. 

